Master Curve of Creep Strength

Miyano et al. propose a method to predict creep strength Oc from the master curve for static strength using the linear cumulative damage law. fs(o) and 4(0) are static and creep failure time, respectively for stress 0. It is supposed that the material experiences a monotonic stress history o(f) for 0 t t where t is the failure time for this stress history. The linear cumulative damage law states  

4(f) Failure time when static strength is Oi fc(f) Failure time when creep strength is Oi From Eqs. 6.10 and 6.11 it follows that  

Applying the iinear cumulative damage law successively to the staircase loading history, it can also be stated  

In order to determine from Eq. 6.15 over the entire stress range, the master curve fore static strength must be avaiiabie. However, due to experimental limitations the stress range below a certain stress iimit cannot be determined. Therefore, it is useful to extrapolate the CSR master curve by an exponential curve. 

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